Bacillus sphaericus (Bacteria), Metarrhizium anisopliae and Culicinomyces spp. (Fungi), Nosema algerae (Protozoa) and Romanomermis culicivorax (Nematoda) are already mass-producible. None of these candidate biocontrol agents have rigid host specificities but their health and environment safety has either been established or is at an advanced stage of evaluation under WHO auspices. None of them had been tried against Simuliidae (blackflies) until RUVP's work with the warm-water mosquito mermithid, R. culicivorax, against these insects over the past two years. This project progressed from the lab at St. John's (1975) to the lab at Bouake, Ivory Coast (1976), to the field in Ivory Coast (1977). The West African field trials have involved the onchocerciasis vector, Simulium damnosum, and the 1977 field project, still in progress, is yielding highly encouraging results. Parallel studies are being initiated at RUVP using a Wyoming cold-water worm, R. neilseni (object: colonization and lab and field trials against northern biting flies). As the WHO Collaborating Centre on Biological Control for the Identification, Ecology and Safety on Non-Target Organisms (one of an international complex of labs designated by WHO for coordinated investigations of health and environmental acceptability of biocontrol agents), RUVP is well-placed for evaluating the above and other such organisms against blackflies. Moreover, our testing of insect growth regulators against Simuliidae and co-existing freshwater life has enhanced our potential for rearing blackflies in the lab and furnished us with equipment and expertise directly relevant to the studies now proposed - bioassays of effects of selected insect pathogens on blackfly larvae and associated aquatic organisms. The test insect will be the North American Simulium venustum, large quantities of the eggs of which are routinely collected locally in summer and stored for hatching and rearing as experimental larvae are needed. Candidate biocontrol agents will be obtained through local collection (some, like Metarrhizium anisopliae, already being worldwide), commercially, or from collaborating labs. Batches of 25-100 larvae will be dosed in 500 ml containers in a highly-efficient and standardized rearing system, and the findings will be processed by log-probit analysis.